Breast cancer: warning signs, risk factors and early detection guide

1. Introduction

Breast cancer begins when cells in breast tissue change and grow out of control, often forming a lump called a tumour. MedlinePlus notes that it can rarely affect men ^[3]. The World Health Organization (WHO) says an estimated 2.4 million women were diagnosed in 2024 and 694,000 died, and it was the most common cancer in women in 164 of 186 countries ^[1].

The good news is that cancers found early, when the lump is small and has not spread to nearby lymph nodes (small glands that filter fluid), are more successfully treated ^[1].

2. Causes and risk factors

The exact cause is often unknown. Cancer involves changes in the genetic material of cells, and some of these changes are inherited ^[3]. WHO and MedlinePlus list these risk factors ^{[1, 3]}:

• Being female and growing older. About 80% of cases occur in women with no risk factor other than sex and age over 40 ^[1].
• A family history, or a personal history of breast cancer or some non-cancerous breast disease. WHO adds that most women diagnosed have no known family history ^{[1, 3]}.
• Inherited changes in genes such as BRCA1, BRCA2 and PALB2, which can also raise the chance of ovarian cancer ^{[1, 3]}.
• Dense breast tissue ^[3].
• Longer lifetime exposure to the hormone oestrogen, such as a first period at a young age, a first birth at an older age or never giving birth, and a late menopause ^[3].
• Hormone therapy after menopause, radiation to the chest, obesity, alcohol and tobacco ^{[1, 3]}.

3. Signs and symptoms

The NHS lists these possible signs ^[2]:

• A lump or swelling in the breast, chest or armpit
• Dimpling of the skin, which may look like orange peel
• Skin that looks red on lighter skin, or darker than usual on darker skin
• A change in the size or shape of one or both breasts
• Nipple discharge, which may contain blood, when you are not pregnant or breastfeeding
• A nipple that turns inward, or a rash on the nipple that may look like eczema

Pain in the breast or armpit can occur, but cancer can also be painless, and breast pain alone is not usually a sign of cancer ^[2]. WHO says a lump is often painless ^[1]. Most lumps are not cancer, but see a doctor even if the lump does not hurt ^{[1, 2]}. Checking your breasts regularly helps you notice changes ^[2].

4. Early detection and screening

WHO describes two routes to early detection. Early diagnosis means recognising signs, getting prompt medical evaluation and being referred quickly to treatment. Screening means testing healthy people, usually with a mammogram (an X-ray test of the breast), often in women aged 50 to 69 ^[1]. MedlinePlus says regular mammograms may find breast cancer at an early stage when it is easier to treat ^[3]. The CDC advises talking to your doctor about when to start and how often to have mammograms. A strong family history can point to inherited gene changes, so tell your doctor about it ^[4].

5. Diagnosis

A doctor will ask about symptoms and family history and may examine your breasts and armpits. The NHS says you can have a friend or a member of staff with you, and a referral to a breast clinic does not mean you have cancer ^[2]. Tests can include a mammogram, ultrasound or MRI scan and a biopsy, in which a small tissue sample is examined ^[3]. Special tests on cancer cells, such as for hormone receptors and a protein called HER2, guide treatment ^{[1, 3]}. Staging checks whether the cancer has spread ^[3].

6. Treatment

Treatment depends on the type and spread, and is planned by a team of specialists. It often combines surgery, radiation therapy and medicines ^{[1, 3]}:

• Surgery: a lumpectomy removes the cancer and some nearby tissue, while a mastectomy removes the whole breast ^{[1, 3]}.
• Radiation therapy targets any remaining cells and lowers the chance of return ^[1].
• Medicines can include hormone therapy, chemotherapy, targeted therapy and immunotherapy, depending on the cancer's features ^{[1, 3]}.

WHO says treatment works best when it is started early and completed in full ^[1]. WHO also says that exercise, diet and psychological support before treatment, and help finding your way through care, improve outcomes ^[1].

7. Lowering your risk

Some risk cannot be changed, but MedlinePlus suggests keeping to a healthy weight, limiting alcohol, exercising regularly, breastfeeding when possible and limiting hormone therapy ^[3]. People at high risk because of gene changes can talk to their doctor about genetic counselling and risk-reducing options ^{[1, 3, 4]}.

8. When to see a doctor

The NHS advises seeing a doctor if you have a lump or swelling in the breast, chest or armpit, any breast or nipple change that is not normal for you, or breast or armpit pain together with close relatives who have had breast or ovarian cancer ^[2]. These signs are often caused by other conditions, but they should be checked, because finding cancer early can make it easier to treat ^[2].

In an emergency, call your local emergency number (112 in India, 911 in the United States).

9. Conclusion

Breast cancer is common, but early detection through awareness, prompt medical review and screening improves outcomes. Learn what is normal for you, act on changes without delay and talk to your doctor about screening and family history.